Exemplary embodiments relate generally to an integrated circuit, and more particularly to a precharge control circuit and an integrated circuit including the same.
A nonvolatile memory device retains data stored in the device even in absence of power supply.
The data in a nonvolatile memory device is programmed or erased through F-N tunneling. More specifically, a floating gate is accumulated with electrons through a program operation, and the electrons accumulated in the floating gate are discharged toward the substrate through an erase operation. The threshold voltage of a memory cell may vary according to the amount of electrons accumulated in the floating gate, and the data can be determined by detecting the level of threshold voltage in a read operation.
FIG. 1 shows the general layout of a memory cell array of a semiconductor memory device.
Referring to FIG. 1, the memory cell array 100 of the semiconductor memory device includes a plurality of memory blocks BK. Each memory blocks BK includes a plurality of cell strings, and a plurality of memory blocks BK may be arranged in rows, e.g., in parallel from top to bottom as shown in FIG. 1, such that columns of the corresponding cell strings can also be formed (that is, the cell strings in each column come from different rows of memory block).
Each column of cell strings is coupled to one of the bit lines BL. Therefore, the length of a bit line would increase with more rows of memory blocks BK.
In general, a bit line is precharged or discharged when a program or read operation is performed in the semiconductor memory device. When the bit line length is elongated too long, the time it would take to precharge or discharge a bit line would become undesirably lengthy. Furthermore, when a power supply voltage is provided at once to precharge the bit line, it would cause the peak current to rise, which may negatively affect the operations of other circuits.
This type of precharge problem is not just limited to the bit line operations, but it may also occur in an integrated circuit having a too heavy load on lines that must be precharged.